Nanoparticle dose and antigen loading attenuate antigen-specific T-cell responses

Area of Science:

• Immunology
• Nanotechnology
• Drug Delivery

Background:

• Current immune suppressants lack specificity, causing side effects.
• Antigen (Ag)-specific tolerance can be induced using carrier systems like poly(lactide-co-glycolide) nanoparticles (PLG-Ag) and splenocytes (SP-Ag).
• Efficacy of tolerance induction varies between carrier platforms.

Purpose of the Study:

• To evaluate the impact of Ag loading and dose of PLG-Ag on Ag presentation.
• To compare PLG-Ag with SP-Ag in a dendritic cell (DC) and T cell coculture system.
• To assess the in vitro and in vivo immune regulation by Ag-carrier systems.

Main Methods:

• Coculture of dendritic cells (DCs) and Ag-restricted T cells with PLG-Ag and SP-Ag.
• Measurement of CD25 expression, cytokine secretion (IL-2, IFNγ, IL-4), and transcription factor (TF) activity (TRACER).
• In vivo validation using delayed-type hypersensitivity (DTH) and experimental autoimmune encephalomyelitis (EAE) mouse models.

Main Results:

• PLG-Ag efficiently presented Ag to DCs, evidenced by high CD25 expression on T cells.
• Cytokine secretion and TF activity varied with Ag loading, dose, and carrier type.
• A threshold of 8 μg/mg Ag loading and 0.5 mg PLG-Ag dose was required for tolerance in vivo.

Conclusions:

• Ag loading and dose are critical parameters for optimizing Ag-carrier systems for immune tolerance.
• PLG-Ag and SP-Ag carriers differentially modulate DC-T cell interactions and TF activity.
• Findings provide insights for translating Ag-carrier systems for treating immune disorders.